From owner-freebsd-net  Fri Dec 13  8: 6: 3 2002
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From: "Guy Helmer" <ghelmer@palisadesys.com>
To: "Petri Helenius" <pete@he.iki.fi>
Cc: <freebsd-net@FreeBSD.ORG>
Subject: RE: libpcap
Date: Fri, 13 Dec 2002 10:05:58 -0600
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Petri Helenius wrote:
> Guy Helmer wrote:
> >I use "sysctl debug.dbf_bufsize=131072" on my appliances to increase the
> >BPF buffer size  to something more reasonable without having to directly
> >modify libpcap.
> >
> Hope you're not disappointed to find out that modifying that parameter has
> no effect when using applications which use libpcap since libpcap always
> sets the buffer size to 32768. (which is exactly the problem I'm
complaining about)

You are right - I misremembered how the BIOCSBLEN ioctl worked.  My
appliances do have a private copy of libpcap with a larger buffer size
because of this problem.

IMHO, it would be better for the libpcap code to query the default BPF
buffer size (BIOCGLEN) and use it if it is larger than the libpcap default
size (32768).  Then libpcap would obey the buffer size set by the sysctl.

Guy


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